Although human alveolar epithelium has long been known to be permeable to insulin, actual diabetes management by insulin administration via lung awaited development of a practical delivery system. A new dry powder insulin formulation and aerosol delivery device permits reproducible pulmonary delivery of rapid-acting insulin in therapeutic amounts with 1-2 inhalations per dose. To compare the safety and efficacy of a regimen using this inhaled insulin (INH) in Type 2 diabetes mellitus poorly controlled on single or combination oral agents, subjects at 10 sites were randomly assigned to receive INH.